This article relates two topics of central importance in modern astronomy – the discovery some 15 years ago of the first planets around other stars (referred to as exoplanets), and the centuries-old problem of understanding the origin of our own solar system, with its planets, planetary satellites, asteroids, and comets. The surprising diversity of exoplanets, of which more than 500 have already been discovered, has required new models to explain their formation and evolution. In turn, these models explain, rather naturally, a number of important features of our own solar system, amongst them the masses and orbits of the ‘terrestrial’ and ‘gas giant’ planets, the presence and distribution of asteroids and comets, the origin and impact cratering of the Moon, and the existence of water on Earth.
Oblique impact cratering experiments in brittle targets: Implications for elliptical craters on the Moon